A Systematic Review of Clinical Epidemiology and Outcomes of Emergency Department-Acute Kidney Injury Found High Incidence and Poor Outcomes

Background: Over half of all community-acquired acute kidney injury (CA-AKI) initially presented to the emergency department (ED), but ED-AKI is poorly characterised, poorly understood, often under-recognised and under-managed. There is no systematic review focusing on ED-AKI. Yet, in-hospital AKI deaths are often associated with suboptimal recognition, management, and documentation. Therefore, we aim to systematically review the incidence, risk factors, and outcomes of emergency department acute kidney injury (ED-AKI), and risk factors of post-ED-AKI mortality globally. Methods: We included published prospective or retrospective observational studies, controlled trials, and systematic reviews reporting AKI in adult ED attendees within 24 hours of ED admission. Iatrogenic causes of AKI from medical interventions were excluded. We used PubMed to identify articles from 1996 to 14 August 2021, and adopted the National Heart, Lung, and Blood Institute (NHLBI) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies to assess risk of bias. We used a forest plot to present the pooled ED-AKI incidence rates and I2 statistics. Other parameters were summarised narratively in a tabular form. Results: We identified six articles using 24 hours from ED admission as the definition for ED-AKI from 2005 to 2018 in high-income settings and one article with a 48-hour timeframe. The pooled incidence of ED-AKI was 20 per 1000 adult ED attendances. Risk factors for ED-AKI included increasing age, nursing home residence, previous hospital admission within 30 days, discharge diagnosis of diabetes, obstructive uropathy, sepsis, gastrointestinal medical conditions, high serum creatinine, bilirubin, C-reactive protein, white blood cell, alanine aminotransferase, low serum sodium or albumin on admission, poor premorbid renal function, antibiotic use, active malignancy, lung disease, hyperlipidaemia, and infection. The crude, all-cause 24-hour mortality rate was 4.56% and one-year mortality was 35.04%. Increasing age and comorbidities including cardiovascular disease and malignancy were associated with higher mortality rates. Conclusion: The review reveals high burden of ED-AKI. Compared to general AKI, ED-AKI has higher mortality rate and different risk factors. Main limitations include limited articles, heterogeneity of incidences, and no confounder adjustment. This calls for further research, red flag identification, and standardized management protocols for ED-AKI.